Compute average - single frame

Through this option DigImage uses the ALU to produce a weighted average over a specified number of frames for a single buffer. The averaging procedure is add the contents of the buffer with the newly digitized image and divide by two. This is repeated until the desired number of video frames has been processed. If the average is to be performed over M frames, then the weightings for each are given by

           Frame           Weighting
           1               1/(2**(M-1))
           2               1/(2**(M-2))
           ...             ...
           M-1             1/4
           M               1/2

Acquire which buffer ?

The user specifies which buffer is to be filled with the average images. Any valid buffer may be used, remembering that buffers in extended memory will be acquired first to buffer 0 and then copied to extended memory.

Average over how many frames ?

This specifies the number of frames over which the average is to be computed. A true average is produced only if averaging over two frames. If more than two frames are specified, then they are weighted in favour of the later frames in the manner indicated above.

Press any key to start

The acquisition process and delay clock are started by pressing any key. Once all the buffers have been acquired, their contents will be written to the specified files (if this was requested) before returning control to the Grab & Display submenu.

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DigImage User Documentation

Stuart Dalziel, last page update: 19 February 1996